The present invention relates to semiconductor integrated circuits and packaging of semiconductor integrated circuits and, more particularly, to a packaged semiconductor die that has many wire bonded connections with a large proportion being power rail wire bonds for supplying a positive supply rail and a ground supply rail to the die.
Semiconductor die packages are typically formed with a semiconductor die mounted on a semiconductor die support such a die pad or flag of a lead frame, or a substrate. External connectors on either the substrate or leads of the lead-frame are wire bonded to die connection pads on the die to provide a means of easily electrically connecting the die to circuit boards and the like. After the connectors and pads are wire bonded, the semiconductor die and bond wires are encapsulated (packaged) in a compound such as a plastics material leaving external pads of the substrate or sections of the leads exposed. The external connectors or exposed leads allow for external electrical connection of the die to a circuit board.
There is always a desire for more or additional external connections to the die and thus the number of external connectors (pin count) is often increased to accommodate increased functionality and power supply rail requirements of the semiconductor die. The external connectors are needed to connect to power rail pads, ground rail pads and data input and output pads of the die. An increase in the number of external connectors typically results in an increased size of the semiconductor die package (footprint), and the requirement of additional wire bonds. The number of power rail wire bonds required for the power supply rail (the positive supply rail and ground rail) to the power rail pads may account for a large proportion of the wire bonds. These power rail wire bonds, which can be as high as 50% of all the wire bonds, may cause stray capacitances with data wire bonds that couple the data input and output pads to the external connectors. Also, the additional lengths of the bond wires may add to stray capacitance effects and also increase the possibility of noise induction. Therefore, it would be desirable to be able to accommodate additional external connections without increasing the chance of noise inductance, cross-coupling, etc.